1. Field of the Invention
The present invention relates to a method for protecting and restoring a link and, more particularly, to a method for protecting and restoring a link using optical label merging and dynamic resource sharing in response to a network load in an optical burst switching (OBS) network.
2. Background of the Related Art
A rapid increase in Internet traffic and demands for Quality of Services (QoS) and discriminative application services have brought about rapid evolution of optical networks. The current core technique of optical networks is a line switching technique based on dense wavelength division multiplexing (DWDM) that multiplexes and transmits a maximum of 80 wavelengths on a single optical fiber. However, this technique is not efficient because it cannot maximize optical transmission characteristic.
Furthermore, ultra-high speed optical packet switching (OPS) is the most appropriate technique for accommodating Internet traffic. However, this technique has many technical limitations in that there exist no buffer for optical purposes and the current switching time of optical device is longer than a packet transmission time.
To address these problems, there has been proposed optical burst switching (OBS), which is recognized as the most realizable optical switching technique. To implement this OBS technique, studies on a control plane and a burst generation algorithm have been actively carried out. However, there is little or no research in protection and restoration fields.
The liveness probability of the network in communication means capability of solving a fault generated in a network and restoring the function of the network. This is one of essential functions of optical networks for stabilized communication. In consideration of large-capacity high-speed transmission environment enabled by DWDM, the capability of restoring the network function is a very important function because a single link fault may cause a vast amount of data loss in the large-capacity high-speed transmission environment.
In order to increase the liveness probability of the network, a passive protecting and restoring method, easily applied to line switching optical networks, was used. Examples of such conventional protecting and restoring mechanisms include a 1:1 route-based protection and restoration mechanism, a 1:1 link-based protection and restoration mechanism, a 1+1 route-based protection and restoration mechanism, and a 1+1 link-based protection and restoration mechanism. These techniques passively carry out 1:1 duplex transmission for all of transmission routes or allocate spare wavelengths and routes in preparation for disconnection of transmission links, or execute these functions for each link to restore a network having a fault within a minimum period of time.
However, the aforementioned techniques which have been applied to conventional line switching networks are not suitable for OBS networks. For example, the conventional techniques cannot guarantee transmission reliability when protection and restoration are made in the OBS networks in spite of low network efficiency and complicate the structure of OBS networks. Furthermore, it is impossible to operate networks based on various new policies when QoS-based transmission is performed. This is because the OBS networks have both of packet switching and circuit switching characteristics and use one-way signaling such that a transmission channel is reserved and then data bursts are transmitted through the reserved channel.